CN100590963C - Method for driving and controlling universal rotary magnetic field of the medical treatment miniature robot in the body - Google Patents

Abstract

The invention pertains to the technical field of medical engineering and discloses a method for driving and controlling a universally rotating magnetic field of a medical micro-robot in a human body.The method is characterized in that three groups of Helmholtz coils on z, y and x axes are arranged by orthogonal nesting so as to ensure that respective combined inductance is equal and the amplitudeof intensity of magnetization of a harmonic magnetic field generated respectively is equal when the three groups of coils are driven by the same harmonic current. The relevant amplitude of an axis azimuth angle of the robot and a same frequency sine harmonic driving current of a phase are overlapped to form a spatial universally and evenly revolving magnetic field corresponding to the revolving axis of the azimuth angle in a certain space surrounded by the orthogonal Helmholtz coils on the three axes. The self-rotating direction of the universally rotating magnetic field can be changed by changing the current frequency to adjust the revolution of the magnetic field and changing the orthogonal Helmholtz coils on the three axes to drive the current direction. The method of the invention hasthe beneficial effects that the method is applicable to a bending inner environment of the human body and can realize a plurality of functions of rotation, going forward and backward and speed adjusting, etc., of the robot in the human body, and the positioning operation in the human body.

Description

Medical miniature robot method for driving and controlling universal rotary magnetic field in the body

Technical field

The invention belongs to the engineering in medicine technical field, relating to a kind of applying with the robot axis azimuth to three nested Helmholtz coil devices of quadrature respectively is the same frequency sinusoidal signal electric current of the related amplitude value and the phase place of input variable, stack forms the rotation universal rotary magnetic field consistent with robot axis in the certain space that three mutually orthogonal nested Helmholtz coil devices surround, by azimuthal change, can realize that embedded diametrical magnetization neodymium iron boron magnetic body spiral precession medical miniature robot drives the basic skills of walking along any direction in the body.

Background technology

The operating environment of medical Micro-Robot is the interior enteron aisle of body, urinary system, blood vessel etc. in the body, shape complexity in the gentle elastic wall environmental organization of its tubulose, cranky, the space is narrow and small, and complicated non-structured fluid environment has brought great difficulty for the ACTIVE CONTROL and the operation of Micro-Robot.In order gentle elasticity soft tissue not to be caused wound and to enter depths in the body, require Micro-Robot in no cable drive mode, enter and withdraw from depths in the body reliably by moving about, and can realize operations such as diagnosis, interventional therapy safely subtly.Medical robot does not have the cable Driving technique to improving human longevity and quality of life in the body, avoid outside operation that human body is caused wound even disables and have important scientific meaning, can alleviate the patient suffering, shorten rehabilitation duration, reduce medical expense, will produce influence greatly the development of engineering in medicine.

No cable type of drive can significantly improve trafficability characteristic, fail safe and the reliability of body inner machine people in complex environment, so Micro-Robot does not have cable and drives and to have become international main development trend.People such as Japan K.Ishiyama have proposed to utilize three Helmholtz coils that space rotating magnetic field is provided, act on the embedded diametrical magnetization neodymium iron boron magnetic body of capsule, the technical scheme that precession drives under the capsule surface threaded function, but not introducing how producing space rotating magnetic field, also being in confidential state at present.This driving method requires the rotation in inner rotary magnetic field and the dead in line of robot, effectively drive machines people precession walking, therefore in crooked environment, require the axis in inner rotary magnetic field to adjust arbitrarily, consistent with the axis of robot all the time with the rotation that guarantees rotating magnetic field inside and outside the gentle elastic tube of bending, could realize the driving in the crooked environment in the body.Have not yet to see report about research robot driving method in gentle elastic bending environment.Hefei Intelligent Machinery Inst., Chinese Academy of Scineces proposes axially to spur the technical scheme that capsule robot moves with gradient coil in enteron aisle, this mode still belongs to has the damage formula to drive, pull enteron aisle easily, this scheme will be adjusted the relative position of sick bed and field system in addition, has brought sense of discomfort to the patient.Unquestionable universal inner rotary magnetic field not damaged precession type of drive has more practical prospect.

The human body soft tissue environment is cranky, in order to adapt to the driving in the crooked environment, research can be rotated the driving method of the universal rotary magnetic field that axis can adjust arbitrarily according to the concrete condition of crooked environment, and development is the key of problem based on the universal rotary magnetic field generating means of this driving method.Could adjust according to the crooked situation of gentle elastic pipeline like this, make the rotation of universal rotary magnetic field consistent, realize the driving in the complicated bend environment in the body with the axis direction of robot.American documentation literature proposes a kind of method and apparatus that the high frequency rotating magnetic field is provided, and the sinusoidal signal electric current that the position is differed 90 degree is sent into respectively in the Helmholtz coil of two quadratures, has just produced rotating magnetic field.

Below in conjunction with accompanying drawing 2, illustrate that diaxon quadrature Helmholtz coil produces the principle of rotating magnetic field.To diaxon quadrature Helmholtz coil when to feed same frequency and phase difference be 90 ° sinusoidal signal electric current, it is 90 ° multifrequency sinusoid AC magnetic field that two groups of coils can produce same frequency, phase difference when respectively.Adopt two groups of identical quadrature Helmholtz coils of induction reactance, the magnetic flux density amplitude of the harmonic field of generation is identical, and then the magnetic vector of diaxon magnetic-field component stack back generation is the time dependent rotating magnetic field of direction.

The rotating magnetic field that diaxon quadrature Helmholtz coil magnetic vector stack back produces is as follows:

${\stackrel{\&CenterDot;}{B}}_0\left(\mathrm{\&omega;t}\right)={\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="C2008100111100014H2.png"\; state="\{\{state\}\}">B</figure-callout>}}_0\cos \mathrm{\&omega;t}+i\&CenterDot;{\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="C2008100111100014H2.png"\; state="\{\{state\}\}">B</figure-callout>}}_0\sin \mathrm{\&omega;t}$

Wherein, B ₀Be the amplitude of rotating magnetic field magnetic flux density, ω is the angular speed of rotating magnetic field, B ₀Cos ω t is the t magnetic flux density in x axial coil magnetic field constantly, B ₀Sin ω t is the t magnetic flux density in y axial coil magnetic field constantly.The harmonic wave drive current that applies to two coils is respectively:

Wherein, I ₀Be the amplitude of the sinusoidal signal electric current that feeds in two groups of quadrature Helmholtz coils, ω is the angular speed that applies the sinusoidal signal electric current, and the frequency that applies the sinusoidal signal electric current is

Frequency by regulate loading the sinusoidal signal electric current can controlling magnetic field rotary speed, can control the size of magnetic flux density by changing the amplitude that loads the sinusoidal signal electric current.

The combination array that the Helmholtz coil of three pairs of axis mutually orthogonals of another american documentation literature proposition is nested into drives every pair of Helmholtz coil respectively, can realize the demagnetization of three vertical direction.Do not find as yet that by retrieval three quadrature Helmholtz coil nested groups produce the correlative study document of space universal rotary magnetic field.

In sum, universal rotary magnetic field Driving technique in space is that microrobot drives in crooked environment and the key technology of practicability in the body.At present, the someone proposes Driving technique scheme and the realization approach of body inner machine people based on universal rotary magnetic field as yet, this technical application has a extensive future, in case make a breakthrough, can apply miniature screw drives machine people in the body that universal rotary magnetic field drives embedded diametrical magnetization neodymium iron boron magnetic body external.The spiral ribs robot is particularly suitable for the driving in the big viscous liquid; can form the thin diaphragm of one deck dynamic pressure by soft tissue in spiral ribs and the body; carry out not damaged and drive, do not make based on there being wound in the body of universal rotary magnetic field ACTIVE CONTROL and spy on the dream of diagnosis, interventional therapy and come true.

Summary of the invention

The technical scheme that the present invention will solve provides a kind of driving method and concrete operations approach that produces the space universal rotary magnetic field, to realize comprehensive driving walking and the attitude control in the crooked in vivo complex environment of embedded neodymium iron boron inner driver spiral atraumatic medical microrobot.

Technical scheme of the present invention is:

Three groups of mutually orthogonal Helmholtz coils of axis are nested together, constitute the three nested Helmholtz coil magnetic field superposition of quadrature devices (c), its area of space surrounds sick bed (b) and patient (a) torso portion, apply same frequency sinusoidal signal electric current with robot motion azimuth related amplitude value and phase place to three Helmholtz coil groups respectively by outer driving governor (d), be superposed to the rotation even universal rotary magnetic field consistent in certain zone by three quadrature Helmholtz coils, realize the drive controlling in the crooked in vivo environment of medical miniature robot with robot motion's direction.Desiring the travel direction angle with the place ahead of predicting in the differently curved in vivo environment of robot is input, by driving three mutually orthogonal nested Helmholtz coil magnetic field superposition devices (c), can realize the direction adjustment of the rotation of universal rotary magnetic field easily, reach and the corresponding to purpose of robot motion's deflection, realize the drive controlling of body inner machine people along different directions.

Can superpose out the vector of any direction of three components of orthogonal space therefore in order to produce the space universal rotary magnetic field, needs to add the 3rd Helmholtz coil.Produce at reference diaxon quadrature Helmholtz coil on the basis of the fixing rotating magnetic field principle of rotation, by controlling the loading relation of the sinusoidal signal electric current of related amplitude value and phase place between three quadrature Helmholtz coil groups, can produce the adjustable space universal rotary magnetic field of rotation.

Below in conjunction with accompanying drawing 3, illustrate that three quadrature Helmholtz coils produce the principle of space universal rotary magnetic field.The mikey vector Be the direction of motion vector of Micro-Robot, α wherein, beta, gamma is respectively

With the x of space card Deere coordinate system, y, the deflection of z axle promptly is the direction that the requirement stack produces the universal rotary magnetic field rotation.With reference to the principle of stacking of diaxon Helmholtz coil generation rotating magnetic field, need be at vector

Vertical plane in seek two orthogonal unit vectors

With

As long as having phasic difference along these two unit vectors is 90 ° sinusoidal magnetic field component, the generation rotation direction that just can superpose is The space universal rotary magnetic field.

By space analysis geometry as can be known, the mikey vector can be represented with direction cosines.Choose vector

In the xoy plane and perpendicular to vector Projection in this plane, then vector

Perpendicular to vector Through the vector of deriving Can be expressed as

Choose vector

In the noz plane, and perpendicular to vector

Because vector Perpendicular to Plane n oz, so vector And vector

Also vertical mutually, therefore vectorial

And vector

Be two vectors trying to achieve, satisfy the requirement that produces rotating magnetic field, carry out vector below Find the solution.

By vector Position feature, establish vector

Be (x ₂, y ₂, sin γ), x wherein ₂, y ₂Be respectively in the direction cosines of x, y axle, find the solution vector

Process find the solution both direction cosine x exactly ₂, y ₂Character and the orthogonal analytic relationship formula of two space vectors by direction cosines have:

$\left\{\begin{array}{c}{x}_2^2+{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C2008100111100014H2.png,C2008100111100015H2.png"\; state="\{\{state\}\}">y</figure-callout>}}_2^2+{\sin }^2\mathrm{\&gamma;}=1\\ x_2\&CenterDot;\frac{\cos \mathrm{\&beta;}}{\sin \mathrm{\&gamma;}}+{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C2008100111100014H2.png,C2008100111100015H2.png"\; state="\{\{state\}\}">y</figure-callout>}}_2\&CenterDot;(-\frac{\cos \mathrm{\&alpha;}}{\sin \mathrm{\&gamma;}})=0\end{array}\right.---\left(2\right)$

Try to achieve

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="2"\; label="x"\; filenames="C2008100111100014H2.png,C2008100111100015H2.png"\; state="\{\{state\}\}">x</figure-callout>}}_2=\mathrm{ctg\&gamma;}\&CenterDot;\cos \mathrm{\&alpha;}\\ {\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C2008100111100014H2.png,C2008100111100015H2.png"\; state="\{\{state\}\}">y</figure-callout>}}_2=\mathrm{ctg\&gamma;}\&CenterDot;\cos \mathrm{\&beta;}\end{array}\right.$ Or $\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="2"\; label="x"\; filenames="C2008100111100014H2.png,C2008100111100015H2.png"\; state="\{\{state\}\}">x</figure-callout>}}_2=-\mathrm{ctg\&gamma;}\&CenterDot;\cos \mathrm{\&alpha;}\\ {\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C2008100111100014H2.png,C2008100111100015H2.png"\; state="\{\{state\}\}">y</figure-callout>}}_2=-\mathrm{ctg\&gamma;}\&CenterDot;\cos \mathrm{\&beta;}\end{array}\right.$

According to vector With vector

Orthogonal relation has: x ₂Cos α+y ₂Cos β+sin γ cos λ=0 is separated substitution respectively above vertical relation formula mutually with above two groups and is verified:

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="2"\; label="x"\; filenames="C2008100111100014H2.png,C2008100111100015H2.png"\; state="\{\{state\}\}">x</figure-callout>}}_2=-\mathrm{ctg\&gamma;}\&CenterDot;\cos \mathrm{\&alpha;}\\ {\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C2008100111100014H2.png,C2008100111100015H2.png"\; state="\{\{state\}\}">y</figure-callout>}}_2=-\mathrm{ctg\&gamma;}\&CenterDot;\cos \mathrm{\&beta;}\end{array}\right.$

So vector Direction cosines be: (ctg γ cos α ,-ctg γ cos β, sin γ).

When along two orthogonal vectors

And vector

Magnetic flux density component when being respectively following form, just stackable generation rotation direction is

The space universal rotary magnetic field.

${\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="C2008100111100015H2.png"\; state="\{\{state\}\}">B</figure-callout>}}_1={\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="C2008100111100014H2.png"\; state="\{\{state\}\}">B</figure-callout>}}_0\&CenterDot;(i\&CenterDot;\frac{\cos \mathrm{\&beta;}}{\sin \mathrm{\&gamma;}}-j\&CenterDot;\frac{\cos \mathrm{\&alpha;}}{\sin \mathrm{\&gamma;}})\&CenterDot;\cos \mathrm{\&omega;t}---\left(3\right)$

B ₂＝B ₀(·-i·ctgγ·cosα-j·ctgγ·cosβ+k·sinγ)·sinωt (4)

Therefore only need load respectively the electric current in the following formula (5) in three quadrature Helmholtz coils, just can make the rotation of universal rotary magnetic field of generation consistent with the axis of robot, drive machines people is along vector

Direction motion.

$\left\{\begin{array}{c}{I}_x={\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="C2008100111100014H2.png"\; state="\{\{state\}\}">I</figure-callout>}}_0\&CenterDot;(\frac{\cos \mathrm{\&beta;}}{\sin \mathrm{\&gamma;}}\&CenterDot;\cos \mathrm{\&omega;t}-\mathrm{ctg\&gamma;}\&CenterDot;\cos \mathrm{\&alpha;}\&CenterDot;\sin \mathrm{\&omega;t})\\ I_y=I_0\&CenterDot;(-\frac{\cos \mathrm{\&alpha;}}{\sin \mathrm{\&gamma;}}\&CenterDot;\cos \mathrm{\&omega;t}-\mathrm{ctg\&gamma;}\&CenterDot;\cos \mathrm{\&beta;}\&CenterDot;\sin \mathrm{\&omega;t})\\ I_z=I_0\&CenterDot;\sin \&CenterDot;\mathrm{\&gamma;}\sin \mathrm{\&omega;t}\end{array}\right.---\left(5\right)$

Conversion gets to following formula

Wherein, α, beta, gamma are respectively vector With the x of space card Deere coordinate system, y, the deflection of z axle,

I ₀Be the amplitude of the sinusoidal signal electric current that feeds in three groups of quadrature Helmholtz coils, ω is the angular speed that applies the sinusoidal signal electric current, and the frequency that applies the sinusoidal signal electric current is $f=\frac{\mathrm{\&omega;}}{2\mathrm{\&pi;}}.$

Satisfy the right-hand rule between every shaft current positive direction and the corresponding reference axis.

Formula (6) is the general driving relationship formula that three quadrature Helmholtz coils produce the space universal rotary magnetic field,

Formula (1) is the driving relationship formula that diaxon quadrature Helmholtz coil produces the fixed axis rotating magnetic field, is a special case of formula (6), and visible (6) is correct.

By formula (6) as seen, the amplitude of three quadrature Helmholtz coil loading sinusoidal signal electric currents is directly proportional with the sine of robot motion's deflection, each phase difference that loads sinusoidal signal is also relevant with direction cosines, therefore the direction of motion angle with robot is an input variable, regulate the loading sinusoidal signal current relationship of three quadrature Helmholtz coils, just can produce the corresponding to space of rotation and robot axis universal rotary magnetic field, realize the drive controlling of robot along any direction.

Applied amplitude and the phase place and the azimuth of three road same frequencys by coordinate transform draws to three mutually orthogonal nested Helmholtz coil group devices (cos α, cos β, cos γ) is the sinusoidal signal expression formula of the identical generation space universal rotary magnetic field of essence for other expression-form of the relevant sinusoidal signal functional relation of input variable with formula (6).

Effect of the present invention and benefit are:

By the stackable generation of software programming space universal rotary magnetic field, solved the driving walking problem of the interior medical miniature robot of body along any direction, can realize that the no cable in the crooked in vivo environment of robot drives.The patient can quietly lie down on one's sick bed, the control of operator by universal rotary magnetic field realizes the turning to of body inner machine people, advance, retreat and function such as speed adjustment, the adjustment campaign that has overcome the relative magnetic field of sick bed has in the past improved the reliability and the practicality of body inner machine people control to the discomfort that the patient brings.

Description of drawings

Accompanying drawing 1 is the technical scheme schematic diagram that universal rotary magnetic field device of the present invention is used for vivo inserted medical treatment.

Accompanying drawing 2 is schematic diagrams that diaxon quadrature Helmholtz coil device produces rotating magnetic field

Accompanying drawing 3 is schematic diagrams that three quadrature Helmholtz coils produce the space universal rotary magnetic field.

Accompanying drawing 4 is three Helmholtz coil device and driving control system structure charts that quadrature is nested.

Among the figure: a patient; The b sick bed; Three nested Helmholtz coil magnetic field superposition of quadrature of c device; The d driving governor.

The helicoid inner machine people of 1 embedded diametrical magnetization body; 2 is the Helmholtz coil group of x axle axially;

3 is the Helmholtz coil group of y axle axially; 4 is the Helmholtz coil group of z axle axially;

5 controllers; 6 drivers.

Embodiment

Be described in detail specific embodiments of the invention below in conjunction with technical scheme and accompanying drawing.

Embodiment:

Implementation step of the present invention is as follows:

(1) three spaces that the nested Helmholtz coil group of quadrature surrounds of planning are so that contain human body and sick bed; Adopting axially be the Helmholtz coil group 4 of z axle, axially is that the Helmholtz coil group 3 of y axle is the mutually orthogonal nested mount scheme of Helmholtz coil group 2 order from big to small of x axle with axial.

(2) on the basis of the nested mount scheme of above order, finish and axially be the Helmholtz coil group 4 of z axle, axially be the Helmholtz coil group 3 of y axle and axially be the matching Design of the Helmholtz coil group 2 of x axle, the amplitude of the harmonic field magnetic flux density that separately the combination induction reactance of three groups of Helmholtz coils when same sinusoidal signal current drives is equated and produce separately is identical, guarantees that the magnetic field after the three-axle magnetic field component superposes is uniform space rotating magnetic field.The nested from big to small installation of size by three groups of Helmholtz coil groups, in order to compensate the magnetic field intensity loss in big hub of a spool zone, the technological approaches of taking is that the number of turn that increases the Helmholtz coil group 3 of the Helmholtz coil group 4 of z axle and y axle accordingly makes the amplitude of three groups of Helmholtz coils harmonic field magnetic flux density of three groups of coils when same sinusoidal signal current drives identical; In order to compensate the few little problem of induction reactance of the small coil number of turn, certain corresponding inductance is concatenated into respectively on the Helmholtz coil group 2 of the Helmholtz coil group 3 of y axle and x axle, three groups of Helmholtz coils separately combination induction reactance when same sinusoidal signal current drives is equated, finish matching Design.

(3) design of controller 5 is adopted and is had the core devices of the three road independent DDS chip AD9959 that export as signal generating circuit, utilize Single-chip Controlling AD9959 to export the sinusoidal signal that the identical relevant phase place of three tunnel frequencies and amplitude satisfy the functional relation of formula (6), three road signals are after filtering is amplified, pass through power amplification driver 6 again, to export enough big electric current, drive three mutually orthogonal Helmholtz coils respectively, every group of coil all produces a space magnetic field, magnetic direction is also mutually orthogonal, after the quadrature magnetic vector stack in three magnetic fields, in the space that three axial coils are surrounded, form a uniform rotating magnetic field.

Wherein, α, beta, gamma are respectively vector

With the x of space card Deere coordinate system, y, the deflection of z axle,

I ₀Be the amplitude of the sinusoidal signal electric current that feeds in three groups of quadrature Helmholtz coils, ω is the angular speed that applies the sinusoidal signal electric current, and the frequency that applies the sinusoidal signal electric current is $f=\frac{\mathrm{\&omega;}}{2\mathrm{\&pi;}}.$

Satisfy the right-hand rule between every shaft current positive direction and the corresponding reference axis.

(4) the signal generating circuit periphery is the man-machine interaction circuit, comprises keyboard circuit, display circuit and serial communication circuit.Keyboard circuit is responsible for keyboard is scanned, accept corresponding key assignments from keyboard, comprise the setting of output signal frequency, amplitude and phase place and the value of various function keys, key assignments is sent into behind the single-chip microcomputer through behind the interpretation of programs, send into the DDS chip as instructions such as frequency control word, amplitude control word and phase control words, AD9959 promptly carries out the adjustment output signal frequency after receiving instruction, corresponding operatings such as amplitude and phase place, and each road output signal can be modulated separately.Display circuit can show the parameters value of output signal and the key assignments of keyboard input, is convenient to output signal is controlled.Can communicate by letter with upper PC by the serial communication circuit single-chip microcomputer, under the virtual instrument interface in PC, the parameters of system output signal can be set, can also read single-chip microcomputer current working state and information.

(5) when needs produce the magnetic direction vector be

During the space rotating magnetic field of (cos α, cos β, cos γ), α wherein, beta, gamma is respectively

With x, y, the deflection of z axle, at first with direction angle alpha, the value of beta, gamma input PC, PC, is tried to achieve at x through computing according to equation (6), y, when the z direction of principal axis produces the magnetic field that meets the demands, three groups of three tunnel sinusoidal signal I that coil loads respectively _x, I _y, I _zAgain with gained sinusoidal signal I _x, I _y, I _zFrequency, related amplitude value and phase parameter send to single-chip microcomputer by the human-computer interaction interface on the PC, export three tunnel sinusoidal signals that meet the demands by Single-chip Controlling DDS chip AD9959, after the filtering amplification, be loaded into respectively on the corresponding Helmholtz coil, thereby produce magnetic direction be

The space universal rotary magnetic field that meets the demands.

(6) rotating speed of space universal rotary magnetic field can realize that the size of magnetic field intensity is then controlled by the amplitude of electric current by the frequency that changes the output sinusoidal signal.When the universal FR in needs space rotates, only need be with the rotating shaft direction of reversing magnetic field Deflection (π+α), (π+β) is (in the value input PC of π+γ), refresh the waveform parameter of three-way output signal, new current signal is loaded on the coil, can drive the universal space rotating magnetic field that produces reverse rotation, realizes the drive controlling that robot retreats along any direction.

Claims (1)

1, medical miniature robot method for driving and controlling universal rotary magnetic field in the body is characterized in that:

(1) will axially be the Helmholtz coil group (4) of z axle, axially be the Helmholtz coil group (3) and axial Circuit Matching design for three groups of Helmholtz coil groups after the nested installation of the descending order quadrature of Helmholtz coil group (2) of x axle of y axle; The number of turn of the Helmholtz coil group (4) of increase z axle and the Helmholtz coil group (3) of y axle, make when driving with same harmonic current, the amplitude of magnetic flux density that produces harmonic field in the nested Helmholtz coil groups of three groups of quadratures is identical, inductance is concatenated into respectively on the Helmholtz coil group (2) of the Helmholtz coil group (3) of y axle and x axle, three groups of Helmholtz coils separately combination induction reactance when same harmonic current drives is equated, guarantee that the magnetic field after the stack of three-axle magnetic field component is uniform space rotating magnetic field;

The unit vector that ((2)) produce rotating shaft is (cos α, cos β, during cos γ) space universal rotary magnetic field, with direction angle alpha, β, the value of γ is an input variable, and the sinusoidal signal of controlling the identical functional relation that satisfies formula (6) of three road output frequencies drives three Helmholtz coils that axis is mutually orthogonal respectively, forms uniform universal rotary magnetic field in the certain space that it surrounded;

Wherein, α, beta, gamma is respectively unit vector

With the x of space card Deere coordinate system, y, the deflection of z axle,

I0 is the amplitude of the sinusoidal signal electric current that feeds in three groups of quadrature Helmholtz coils, ω is the angular speed that applies the sinusoidal signal electric current, and the frequency that applies the sinusoidal signal electric current is $f=\frac{\mathrm{\&omega;}}{2\mathrm{\&pi;}};$ Satisfy the right-hand rule between every shaft current positive direction and the corresponding reference axis;

The rotating speed of ((3)) space universal rotary magnetic field is realized by the frequency that changes three groups of output sinusoidal signals; The size of magnetic field intensity is controlled by the amplitude of three groups of output sinusoidal signals; When the universal rotary magnetic field reverse rotation of needs space, only need be with the rotating shaft direction of reversing magnetic field

(cos α,-cos β, deflection-cos γ) (π+α), (π+β), (value of π+γ) is that new input variable gets final product, drive three Helmholtz coils that axis is mutually orthogonal respectively according to the sinusoidal signal that satisfies the functional relation of formula (6), produce the universal space rotating magnetic field of reverse rotation, realize the drive controlling that retreats of robot any direction.

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